Exomphalos Diagnosis

Exomphalos, also called an omphalocele, is a defect in the front wall of the baby's tummy. During normal development the abdominal wall closes and the organs sit inside the abdomen. In exomphalos the muscles do not close fully, leaving a gap at the base of the umbilical cord through which abdominal organs — the bowel and, in larger cases, the liver — protrude. These organs are contained within a thin, protective membrane rather than being exposed.

Exomphalos is one of the two main abdominal wall defects, alongside gastroschisis, and affects around 1 in 3,000 pregnancies. It can range from minor (a small defect containing only bowel) to major (a larger defect that also contains the liver).

When the defect is large enough that the liver — as well as the bowel — lies outside the abdomen, it is described as major exomphalos, or 'exomphalos with liver'. Major exomphalos is a bigger defect and usually needs a staged surgical repair after birth, because the abdominal cavity may be too small to return all of the organs in a single operation.

The involvement of the liver is one of several factors, alongside the baby's overall health and any associated conditions, that specialists consider when planning delivery and treatment.

Both are abdominal wall defects in which organs develop outside the tummy, but they are distinct conditions. In exomphalos the organs herniate through the base of the umbilical cord and are covered by a protective membrane. In gastroschisis the defect is usually to the side of the umbilical cord and the bowel is exposed directly to the amniotic fluid, with no covering membrane.

The covering membrane, the position of the defect and the different pattern of associated conditions help specialists tell the two apart on ultrasound.

In early pregnancy the bowel normally moves into the base of the umbilical cord and returns to the abdomen by about 12 weeks. Because of this normal process, a confident diagnosis of exomphalos is usually made after 12 weeks — often at an early fetal or 11–14 week scan, and confirmed at the 20-week anomaly scan.

At London Pregnancy Clinic our early scans include a structured look at the abdominal wall, so suspicion can be raised early and a detailed follow-up arranged.

Exomphalos can occur on its own, but it is also associated with chromosomal conditions such as trisomy 18, 13 and 21, with Beckwith-Wiedemann syndrome, and with heart defects. When exomphalos is isolated the chromosomal risk is low (around 4–5%, roughly 1 in 20), but it is much higher (about 30–70%) when other abnormalities are present.

For this reason, when exomphalos is found, parents are usually offered detailed scanning, a fetal heart scan and genetic testing such as NIPT or a diagnostic test (CVS or amniocentesis) to give the fullest possible picture.

After birth the protective membrane is kept intact and the baby is kept warm and hydrated before transfer to a specialist surgical centre. Small defects can often be repaired in a single operation, in which the organs are returned to the abdomen and the abdominal wall is closed.

Larger defects, including those involving the liver, are usually treated in stages: a protective covering (sometimes called a silo) is placed over the organs and gradually tightened over days to weeks, allowing the abdomen to grow before final closure. Occasionally, if closure is not immediately safe, a patch is left in place and treated later.

The outlook depends largely on the size of the defect and whether there are any associated conditions. For isolated exomphalos — where the baby has no other problems — more than 95% of babies make a full recovery.

When exomphalos occurs alongside a chromosomal condition, a heart defect, a very large defect or prematurity, the outlook is more variable. Early diagnosis and assessment allow the specialist team to plan the safest possible care and to prepare parents for what to expect.